Method for manufacturing liquid discharge head, substrate for liquid discharge head and method for working substrate

Abstract

An ink supply port is opened in an Si substrate on which an ink discharge energy generating element is formed, by anisotropic etching, from a back surface opposite to a surface on which the ink discharge energy generating element is formed. When the anisotropic etching is effected, OSF (oxidation induced laminate defect) remains on the back surface of the Si substrate with OSF density equal to or greater than 2×10 4 parts/cm 2 and a length of OSF equal to or greater than 2 μm.

1. A method for manufacturing a liquid discharge head, comprising:
 a step for preparing an Si substrate having a first surface as an element forming surface and a second surface as a back surface opposite to the first surface;  
 a step for effecting heat treatment by heating of said Si substrate;  
 a step for forming an SiO 2  film on the second surface of said Si substrate;  
 a step for forming an etching start opening portion in said SiO 2  film to expose said Si substrate;  
 a step for forming a liquid discharge energy generating element for generating energy for discharging liquid on the first surface of said Si substrate; and  
 a step for forming a liquid supply port passing through said Si substrate and communicated with the first surface from said etching start opening portion by anisotropic etching of Si using said SiO 2  film as a mask, after said heat treatment step,  
 wherein, before the anisotropic etching is effected, the density of oxidation induced laminate defects existing in an interface between said Si substrate and said SiO 2  film is made to be equal to or greater than 2×10 4  parts/cm 2 .  
 
     
     
       2. A method according to  claim 1 , further comprising a step for forming a member constituting a liquid discharge port for discharging the liquid and a liquid flow path communicated with said liquid discharge port, on the surface of said Si substrate on which said liquid discharge energy generating element is formed. 
     
     
       3. A method according to  claim 1 , wherein, before the anisotropic etching is effected, a length of the oxidation induced laminate defects existing in said interface between said Si substrate and said SiO 2  film is made to be equal to or greater than 2 μm. 
     
     
       4. A method according to  claim 1 , wherein said SiO 2  film is formed by thermal oxidation during the heat treatment. 
     
     
       5. A method according to  claim 1 , wherein the heat treatment is effected at a treatment temperature equal to or less than 1100° C. 
     
     
       6. A method according to  claim 1 , wherein, before the heat treatment at a treatment temperature of A° C. is effected, treatment similar to the heat treatment is effected at a lower temperature of B° C. satisfying A−B≦200° C. 
     
     
       7. A method according to  claim 1 , wherein treatment having a treatment temperature equal to or greater than 1100° C., among the heat treatment, is effected under a gas atmosphere including oxygen. 
     
     
       8. A method according to  claim 1 , wherein said liquid discharge head includes a semiconductor element on said Si substrate, and the heat treatment is effected in a step for forming said semiconductor element. 
     
     
       9. A method according to  claim 8 , wherein said semiconductor forming step is a step of well-driving. 
     
     
       10. A method according to  claim 1 , wherein said Si substrate has a gettering site formed by effecting mechanical damage on the second surface of said Si substrate before said anisotropic etching step. 
     
     
       11. A method according to  claim 1 , wherein a substrate in which the oxygen density is equal to or less than 1.3×10 18  (atoms/cm 3 ) is used as said Si substrate. 
     
     
       12. A method according to  claim 1 , wherein an MCZ substrate is used as said Si substrate. 
     
     
       13. A method according to  claim 1 , wherein a substrate in which the Si crystal face orientation of the surface on which said liquid discharge energy generating element is formed is <100> or <110> is used as said Si substrate. 
     
     
       14. A substrate working method comprising:
 a step for effecting heat treatment by heating of an Si substrate;  
 a step for forming an SiO 2  film on at least one surface of said Si substrate;  
 a step for forming an etching start opening portion in said SiO 2  film to expose said Si substrate; and  
 a step for forming a through-hole passing through said Si substrate from said etching start opening portion by anisotropic etching of Si using said SiO 2  film as a mask, after said heat treatment step,  
 wherein, before the anisotropic etching is effected, the density of oxidation induced laminate defects existing in an interface between said Si substrate and said SiO 2  film is made to be equal to or greater than 2×10 4  parts/cm 2 .  
 
     
     
       15. A substrate working method according to  claim 14 , wherein, before the anisotropic etching is effected, a length of the oxidation induced laminate defects existing in said interface between said Si substrate and said SiO 2  film is made to be equal to or greater than 2 μm. 
     
     
       16. A substrate working method according to  claim 14 , wherein said SiO 2  film is formed by thermal oxidation during the heat treatment. 
     
     
       17. A substrate working method according to  claim 14 , wherein the heat treatment is effected at a treatment temperature equal to or less than 1100° C. 
     
     
       18. A substrate working method according to  claim 14 , wherein, before the heat treatment at a treatment temperature of A° C. is effected, treatment similar to the heat treatment is effected at a lower temperature of B° C. satisfying A−B≦200° C. 
     
     
       19. A substrate working method according to  claim 14 , wherein treatment having a treatment temperature equal to or greater than 1100° C., among the heat treatment, is effected under a gas atmosphere including oxygen. 
     
     
       20. A substrate working method according to  claim 14 , wherein the heat treatment is well-driving. 
     
     
       21. A substrate working method according to  claim 14 , wherein a substrate in which the oxygen density is equal to or less than 1.3×10 18  (atoms/cm 3 ) is used as said Si substrate. 
     
     
       22. A substrate working method according to  claim 14 , wherein an MCZ substrate is used as said Si substrate.